Bleachers (or grandstands) provide seating for an audience for various sporting events, theatrical performances, and other similar events. Permanent bleachers are installed in gymnasiums or other locations where such events are frequent. However, for events that occur on a less frequent basis, temporary bleacher systems may be used. Such temporary bleacher systems are often mounted on some form of mobile framework for ready transport to the location of the event. Once at the appropriate location, the bleacher system can be transitioned from the transport position to a deployed position. Thus, such mobile bleacher systems provide short-term and special event seating without the time and labor required to set up conventional bleachers.
In prior art mobile bleacher systems, hydraulic actuators (or similar mechanical or electromechanical actuators) are often used to transition the bleacher system from the transport position to the deployed position, and vice versa. However, such hydraulic actuators are usually extended during transport and storage, and then retracted to transition the bleacher system to the deployed position. Because the hydraulic actuators are extended, the rods are susceptible to corrosion during transport from exposure to road salt and also susceptible to corrosion from environmental conditions during long periods of storage. Thus, expensive and maintenance-prone rod covers have often been used to address and minimize this problem.
Furthermore, in prior art mobile bleacher systems, complex actuating systems and multiple-step procedures are often required to transition the bleacher system from a transport position to a deployed position, and vice versa.
Furthermore, in prior art mobile bleacher systems, the number of rows in the bleacher system or leg room (pitch) from one seat row to the next is often sacrificed in order to make the bleacher system sufficiently compact for transport.
To address some of these deficiencies of prior art mobile bleacher systems, commonly assigned U.S. Pat. No. 8,296,999, which is incorporated herein by reference, describes a bleacher system (or grandstand) that is comprised of multiple tiers which are mounted on a support structure. The tiers are pivotally mounted to the support structure so that the bleacher system can be readily transitioned from a transport position to a deployed position. In this regard, such transition of the bleacher system from the transport position to the deployed position is achieved through the use of one or more hydraulic actuators (or similar mechanical or electromechanical actuators) that are retracted during transport and storage, and then extended to transition the bleacher system to the deployed position. Thus, the rods are protected from exposure to road salt and environmental conditions during transport and storage. Furthermore, as a result of the configuration of the tiers and their connection to the underlying support structure and each other, deployment requires only a single actuating action. At the same time, there is no sacrifice in the number of rows in the bleacher system or leg room (pitch) from one seat row to the next.
As described in U.S. Pat. No. 8,296,999, in one embodiment, an exemplary bleacher system includes three tiers that are mounted to an underlying support structure, which includes two parallel I-beams (or longitudinal rails) that are spaced from one another and extend the length of the bleacher system, effectively creating a complete trailer frame. Multiple cross members extend between and connect the longitudinal rails along the length of the bleacher system. Wheels and an associated suspension system are mounted to the longitudinal rails to facilitate transport of the bleacher system.
Each tier is then generally constructed of multiple girders at spaced intervals that are operably connected to the underlying support structure. Each girder in each tier supports multiple seat supports and foot board supports, with respective seat planks and foot planks then being secured to the respective seat supports and foot board supports and extending along the length of the bleacher system over such seat supports and foot board supports.
Each girder of the upper tier is connected to a rear strut by a pin connection defining a pivot point. The pivot points defined by the respective pin connections are aligned and effectively define an axis of rotation along the length of the bleacher system. Each rear strut is also connected to the underlying support structure by a pin connection defining another pivot point.
The upper tier is connected to the middle tier by a pin connection defining a pivot point. Again, there are actually multiple such pin connections and associated pivot points that are aligned along the length of the bleacher system that effectively define an axis of rotation along the length of the bleacher system. Furthermore, each girder of the middle tier includes a generally triangular-shaped strut. The pivot point is at a rear corner of this strut, and a lower corner of this strut is mounted to the underlying support structure for rotation about a main pivot point, such that the middle tier can effectively rotate about the main pivot point.
The lower tier is connected to the middle tier by a pin connection defining a pivot point. Again, there are actually multiple such pin connections and associated pivot points that are aligned along the length of the bleacher system that effectively define an axis of rotation along the length of the bleacher system.
With respect to the transition of the bleacher system from the transport position to the deployed position, and vice versa, there is a deployment link support structure that is secured to or integral with the underlying support structure for each hydraulic actuator. Each hydraulic actuator is connected to a respective deployment link support structure at a first end by a pin connection defining a pivot point. The rod of the hydraulic actuator is then connected to the middle tier by a pin connection defining a pivot point.
Furthermore, for each hydraulic actuator, a deployment link is connected to the deployment link support structure by a pin connection defining a pivot point. Each such deployment link extends toward the lower tier with its distal end being connected to a second, shorter deployment link by a pin connection defining a pivot point. The opposite end of this second, shorter deployment link is then connected to the girder of the lower tier by a pin connection defining a pivot point.
In operation, when transitioning from the deployed position to the transport position, each hydraulic actuator is activated in unison, and the respective rods of the hydraulic actuators begin to retract. As the rods retract, the middle tier begins rotating backward about the main pivot point. As a result, the respective pivot points at the pin connections between the middle tier and the lower tier are moved upward, and thus, the lower tier begins rotating toward the middle tier. At the opposite end of the middle tier, the respective pivot points at the pin connections between the middle tier and the upper tier are moved downward. The upper tier thus begins rotating forward. Such simultaneous rotation of the three tiers continues as the rods of the hydraulic actuators retract. Furthermore, once tension is released in the connection between the deployment link and the second, shorter deployment link, these two components begin to rotate and “fold” relative to one another. Rotation of the three tiers ceases when the rods of the hydraulic actuators are fully retracted, at which time the rear struts are each in an upright orientation substantially perpendicular to the underlying support structure, and the bleacher system is in the transport position.
To transition the bleacher system from the transport position back to the deployed position, the respective rods of the hydraulic actuators are extended. The rods effectively push against the middle tier, causing the middle tier to rotate forward about the main pivot point. As a result, the respective pivot points at the pin connections between the middle tier and the lower tier are moved downward, and at the same time, the lower tier begins rotating away from the middle tier. As the lower tier rotates away from the middle tier, the deployment link and the second, shorter deployment link rotate into an aligned position, pushing the lower tier into the deployed position. At the opposite end of the middle tier, the respective pivot points at the pin connections between the middle tier and the upper tier are moved upward. The upper tier thus begins rotating backward. Rotation of the three tiers continues until the rods of the hydraulic actuators are fully extended, and the bleacher system is in the deployed position.
As described in U.S. Pat. No. 8,296,999, in another embodiment, an exemplary bleacher system includes two tiers that are mounted to an underlying support structure, which again includes two parallel I-beams (or longitudinal rails) that are spaced from one another and extend the length of the bleacher system, effectively creating a complete trailer frame. Multiple cross members extend between and connect the longitudinal rails along the length of the bleacher system. Wheels and an associated suspension system are mounted to the longitudinal rails to facilitate transport of the bleacher system.
Each tier is again constructed of multiple girders at spaced intervals that are operably connected to the underlying support structure. Each girder in each tier supports multiple seat supports and foot board supports, with respective seat planks and foot planks then being secured to the respective seat supports and foot board supports and extending along the length of the bleacher system over such seat supports and foot board supports.
Each girder of the upper tier is connected to a rear strut by a pin connection defining a pivot point. The pivot points defined by the respective pin connections are aligned and effectively define an axis of rotation along the length of the bleacher system. Each rear strut is also connected to the underlying support structure by a pin connection defining another pivot point.
The upper tier is connected to the lower tier by a pin connection defining a pivot point. Again, there are actually multiple such pin connections and associated pivot points that are aligned along the length of the bleacher system that effectively define an axis of rotation along the length of the bleacher system. Specifically, each girder of lower tier includes a vertical extension. The pin connection defining the pivot point between the upper tier and the lower tier at each girder is at a first end of this vertical extension, while the opposite end of the vertical extension is connected by a pin connection defining a pivot point to the underlying support structure.
With respect to the transition of the bleacher system from the transport position to the deployed position, and vice versa, a hydraulic actuator is connected to a plate (which is secured to and extends from the support structure) at a first end by a pin connection defining a pivot point. The rod of the hydraulic actuator is then connected to the lower tier by a pin connection defining a pivot point.
In operation, when transitioning from the deployed position to the transport position, when each hydraulic actuator is activated, the respective rods of the hydraulic actuators begin to retract. As the rods begin to retract, the lower tier begins rotating backward. As a result, the respective pivot points at the pin connections between the upper tier and the lower tier are moved downward, and thus, the upper tier begins rotating toward the lower tier. At the same time, the rear struts also begin rotating backward. Such simultaneous rotation of the upper tier and the lower tier continues as the rods of the hydraulic actuators retract. Rotation of the upper tier and the lower tier ceases when the rods of the hydraulic actuators are fully retracted, and the bleacher system is in the transport position.
However, it remains desirable to further simplify the operation of a mobile bleacher system and to incorporate refinements that facilitate the transport and deployment of a mobile bleacher system. Furthermore, some such refinements have applicability to other forms of bleacher systems, including those bleacher systems in which one or more tiers are fixed to the underlying support structure.